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Using brain scans of people suffering from Semantic Dementia — the second most common form of dementia after Alzheimer’s disease in people under 65 — they have found that the front end of the temporal lobe seems to be crucial to conceptual application.

“People have been talking about how the brain encodes concepts for 150 years. We believe we have found it,” Matthew Lambon-Ralph of Manchester University told the annual meeting of the British Association for the Advancement of Science on Wednesday.

Previously the part of the brain dealing with concepts was thought to be Wernicke’s area, which is further back on the temporal lobe, but scans and experiments showed degradation of the front end seemed to be key.

Patients, while being able to carry out everyday mechanical activities like making a cup of tea — as long as it was done in the same order each time — were unable to match abstract ideas to concrete actions.

The brainOne woman accurately drew a duck when a photograph was in front of her, but within a minute of the image being removed she was able to sketch only a four-legged creature with chicken and cat-type features.

“They can identify general types but not specifics,” Lambon-Ralph said, noting that the same applied to smell and touch when taken in isolation.

“I have always been fascinated about how the brain gives meaning. We have made some strides towards that,” he added.

Patients with Semantic Dementia demonstrate a progressive deterioration in their ability to understand and recognize words, while other functions often remain unimpaired.

However, much remains to be discovered about this particular brain function.

Not only do scientists not know which of the two temporal lobes is involved, they also do not know if other parts of the brain are also part of the conceptual process.

Only when they have discovered the answers to those crucial questions will they be able to work out how they can start to develop therapies to counteract the destructive effects of the progressive disease that eventually kills.